"Energy use tends to follow the level of economic activity, and that level declined last year. At the same time, higher efficiency appliances and vehicles reduced energy use even further," said A.J. Simon, an LLNL energy systems analyst who develops the energy flow charts using data provided by the Department of Energy’s Energy Information Administration.
"As a result, people and businesses are using less energy in general."
The estimated U.S. energy use in 2009 equaled 94.6 quadrillion BTUs ("quads"), down from 99.2 quadrillion BTUs in 2008. (A BTU or British Thermal Unit is a unit of measurement for energy, and is equivalent to about 1.055 kilojoules).
Energy use in the residential, commercial, industrial and transportation arenas all declined by .22, .09, 2.16 and .88 quads, respectively.
Wind power increased dramatically in 2009 to.70 quads of primary energy compared to .51 in 2008. Most of that energy is tied directly to electricity generation and thus helps decrease the use of coal for electricity production.
"The increase in renewables is a really good story, especially in the wind arena," Simon said. "It’s a result of very good incentives and technological advancements. In 2009, the technology got better and the incentives remained relatively stable. The investments put in place for wind in previous years came online in 2009. Even better, there are more projects in the pipeline for 2010 and beyond."
The significant decrease in coal used to produce electricity can be attributed to three factors: overall lower electricity demand, a fuel shift to natural gas, and an offset created by more wind power production, according to Simon.
Nuclear energy use remained relatively flat in 2009. No new plants were added or taken offline in this interval, and the existing fleet operated slightly less than in 2008.
Of the 94.6 quads consumed, only 39.97 ended up as energy services. Energy services, such as lighting and machinery output, are harder to estimate than fuel consumption, Simon said.
The ratio of energy services to the total amount of energy used is a measure of the country’s energy efficiency.
Carbon emissions data are expected to be released later this year, but Simon suspects they will tell a similar story.
"The reduction in the use of natural gas, coal and petroleum is commensurate with a reduction in carbon emissions," he said. "Simply said, people are doing less stuff. Therefore, they’re burning less fuel."
Lawrence Livermore National Laboratory has helped to visualize the Energy Information Administration’s U.S. energy data since the early 1970s.
A flow chart detailing the findings is available with annotations in PDF format at: